考察了颗粒粒径、盐酸浓度和浸取温度3个条件对活化煤气化粗渣(简称活化渣)中铝、铁、钙离子浸取率的影响,并对浸取机理进行了研究。实验结果表明,活化渣为钙铝黄长石(2CaO·Al_2O_3·SiO_2)与三氧化二铁(Fe_2O_3)的固溶体,与...考察了颗粒粒径、盐酸浓度和浸取温度3个条件对活化煤气化粗渣(简称活化渣)中铝、铁、钙离子浸取率的影响,并对浸取机理进行了研究。实验结果表明,活化渣为钙铝黄长石(2CaO·Al_2O_3·SiO_2)与三氧化二铁(Fe_2O_3)的固溶体,与盐酸反应后颗粒粒径不断减小,钙离子较铝、铁离子优先浸出,其浸取过程符合化学反应控制的缩芯模型,相应的表观活化能为71.3 k J/mol;钙离子浸出后活化渣颗粒成为疏松多孔材料,铝、铁离子的浸取过程则符合Avrami模型,二者的浸取反应均受内扩散控制,表观活化能分别为24.7 k J/mol和22.5 k J/mol。展开更多
This work deals with isothermal and non-isothermal crystallization kinetics of electrically conductive polyvinylidene fluoride/poly(ethylene terephthalate) (PVDF/PET) based composites. It completes our previous work i...This work deals with isothermal and non-isothermal crystallization kinetics of electrically conductive polyvinylidene fluoride/poly(ethylene terephthalate) (PVDF/PET) based composites. It completes our previous work in which we related the crystallinity of these conductive PVDF/PET based composites to their through-plane resistivity [1]. Isothermal crystallization was described using the logarithmic form of the Avrami equation and it was observed that the crystallization rate of the PVDF phase inside the composite became slower compared to that of neat PVDF. In non-isothermal crystallization, the Avrami exponent of PVDF phase did not show any noticeable variation;however, that of PET phase, which contains the major part of the conductive carbon black (CB) and graphite (GR) additives, showed an evident decrease compared with neat PET. It was also observed that, at the same cooling rate, the crystallization rate of PVDF and PET phases inside the composite was slower than that of neat PVDF and PET.展开更多
Poly(3-hydroxybutyrate) (PHB) is a natural biopolyester accumulated in microbial cells as tiny amorphous granules. The nano- micro-particles have a variety of potential applications and behave differently in different...Poly(3-hydroxybutyrate) (PHB) is a natural biopolyester accumulated in microbial cells as tiny amorphous granules. The nano- micro-particles have a variety of potential applications and behave differently in different environments. In this work, the in situ crystallization of native PHB granules was investigated under different environmental conditions. The isothermal crystallization kinetics of the granules was shown to follow Avrami’s equation. The model parameter describing crystal growth is a function of temperature or pH and estimated from in situ crystallization measurements with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Empirical equations describing crystal growth are derived for the parameter values. PHB granules heated at 80-140°C in acidic solution (pH 2) up to 4 hr showed an increase in crystallinity from about 5% to 35% and moderate particle aggregation. PHB granules suspended in alkaline solutions (pH 9-12) at room temperature up to 4 hr showed an increase in crystallinity up to 45% and very little particle aggregation. It was found that the amorphousness of PHB granules in vivo is stabilized by water, lipids and proteins. Upon removal of these impurities, partial crystallization is induced which may inhibit extensive particle aggregation.展开更多
基金the financial support on this research from the Talent Training Program of Yunnan Province, China (No. 202005AC160041)the Major R&D Project of Yunnan Province of China (No. 202002AB0800020102)。
文摘采用湿法冶金从废旧LiFePO_(4)正极粉末中回收有价金属锂和铁,回收产物作为原料制备磷酸铁锂。通过优化浸出工艺参数,在丙酮酸浓度为3.0 mol/L、H_(2)O_(2)体积为2 m L、固液比为0.1 g/m L、反应温度为80℃以及反应时间为20min的条件下,Li的浸出效率达到96.56%。采用XRD、XPS、FE-SEM和EDS对浸出残渣进行表征。结果表明,浸出残渣为FePO_(4),Fe/P摩尔比为0.974。将浸出液的pH值调整到12.0,并在80℃搅拌2 h后,浸出液中的Li通过原位沉淀以Li_(3)PO_(4)形式回收,其纯度为96.5%(质量分数)。丙酮酸/H_(2)O_(2)溶液浸出Li的反应动力学数据符合Avrami模型(R^(2)>0.95)。Li浸出过程的活化能较低,表明扩散限制浸出过程中的反应速率。
文摘考察了颗粒粒径、盐酸浓度和浸取温度3个条件对活化煤气化粗渣(简称活化渣)中铝、铁、钙离子浸取率的影响,并对浸取机理进行了研究。实验结果表明,活化渣为钙铝黄长石(2CaO·Al_2O_3·SiO_2)与三氧化二铁(Fe_2O_3)的固溶体,与盐酸反应后颗粒粒径不断减小,钙离子较铝、铁离子优先浸出,其浸取过程符合化学反应控制的缩芯模型,相应的表观活化能为71.3 k J/mol;钙离子浸出后活化渣颗粒成为疏松多孔材料,铝、铁离子的浸取过程则符合Avrami模型,二者的浸取反应均受内扩散控制,表观活化能分别为24.7 k J/mol和22.5 k J/mol。
文摘This work deals with isothermal and non-isothermal crystallization kinetics of electrically conductive polyvinylidene fluoride/poly(ethylene terephthalate) (PVDF/PET) based composites. It completes our previous work in which we related the crystallinity of these conductive PVDF/PET based composites to their through-plane resistivity [1]. Isothermal crystallization was described using the logarithmic form of the Avrami equation and it was observed that the crystallization rate of the PVDF phase inside the composite became slower compared to that of neat PVDF. In non-isothermal crystallization, the Avrami exponent of PVDF phase did not show any noticeable variation;however, that of PET phase, which contains the major part of the conductive carbon black (CB) and graphite (GR) additives, showed an evident decrease compared with neat PET. It was also observed that, at the same cooling rate, the crystallization rate of PVDF and PET phases inside the composite was slower than that of neat PVDF and PET.
文摘Poly(3-hydroxybutyrate) (PHB) is a natural biopolyester accumulated in microbial cells as tiny amorphous granules. The nano- micro-particles have a variety of potential applications and behave differently in different environments. In this work, the in situ crystallization of native PHB granules was investigated under different environmental conditions. The isothermal crystallization kinetics of the granules was shown to follow Avrami’s equation. The model parameter describing crystal growth is a function of temperature or pH and estimated from in situ crystallization measurements with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Empirical equations describing crystal growth are derived for the parameter values. PHB granules heated at 80-140°C in acidic solution (pH 2) up to 4 hr showed an increase in crystallinity from about 5% to 35% and moderate particle aggregation. PHB granules suspended in alkaline solutions (pH 9-12) at room temperature up to 4 hr showed an increase in crystallinity up to 45% and very little particle aggregation. It was found that the amorphousness of PHB granules in vivo is stabilized by water, lipids and proteins. Upon removal of these impurities, partial crystallization is induced which may inhibit extensive particle aggregation.
